Activity – Discovering Ohm’s Law Using Edison
Resistors are devices that slow the flow of electrons through a circuit. Slowing the flow of
electrons allows us to control the amount of current and voltage going into a circuit, and it also
allows us to convert electricity into some form of useful energy like heat or light.
When the electrons pass across a resistor they lose energy (electric potential decreases). This
difference in electric potential (potential difference) can be measured using a voltmeter.
German physicist Georg Ohm discovered a relation between the resistance (R) of an object, the
potential difference (V) across the object and the current (I) flowing through the object.
Purpose: Use Edison Software to determine the relationship between V, I, and R.
Procedure:
1. Using the Edison software create the following circuit
2.
3.
4.
5.
6.
Double click the light bulb and set the voltage to 4 V.
Double click the power supply and change the voltage to 1 V.
Record the voltage and the current
Repeat steps 3 and 4 changing the voltage by one each time until the light bulb burns out
Complete steps 2 – 5 for a 8 V light bulb and a 12 V light bulb
Results:
4 V light bulb
Current (A)
8 V light bulb
Current (A) Voltage (V)
Voltage (V)
12 V light bulb
Current (A) Voltage (V)
Analysis:
1. Input the data into Microsoft Excel
2. Plot the data and linearize it to determine the line of best fit and the slope (Current on x –
axis, Voltage on y – axis)
3. Complete step 2 for the other two sets of data
Questions:
1. What is the relationship between the potential difference and the current for each of the
light bulbs? How do you know?
2. Write the equations of the lines that represents each of the data sets (Be sure to use the
correct variables)
3. What is the slope of each of the lines?
4. Ohm’s Law states that the potential difference and the current are related to each other
by the resistance. Which part of the equation must represent the resistance in each
case?
5. Write a general statement of Ohm’s Law in word form and in equation form.
6. When did the light bulb ‘burn out’ in each of the situations? What caused this?
7. Comment on the relationship between resistance and current. Use this relationship to
discuss what would occur to the current and the voltage if the resistance in a circuit
increases or decreases.